A weapons depot belonging to the Popular Mobilization Forces (PMF) at al-Balad military base in Saladin province was rocked by explosions on Tuesday night, leaving the base engulfed in flames.

The explosion is one of a series to have hit bases belonging to Iran-backed militias in recent weeks.

The depot belongs to Iranian-backed PMF militia Kataib Hezbollah, former spokesperson for the group Karim Noori told Rudaw on Tuesday.

“The reason of the fire and the explosions inside the weapons depot near al-Balad air base is still unknown,” Noori said.

Investigation into the cause of the incident is ongoing, he added.

Improper storage of weapons has been ruled out as a potential reason for the explosion, Saladin MP Muhammed Baldawi told Rudaw. He suggested that al-Balad had instead been targeted in an attack.

“Both the Iraqi forces and the PMF are present at the base. There are also US F-16 jet trainers,” Baldawi told Rudaw on Tuesday.

“There are no casualties reported, but PMF weapons have been completely destroyed,” he added.

Iraqi Defense Minister and Iraqi Army chief of staff Najih al-Shimari arrived to al-Balad base on Tuesday night to investigate, according to the Iraqi Ministry of Defense.

Bases belonging to the PMF, otherwise known as Hashd al-Shaabi, have faced a series of mysterious attacks in recent weeks.

On August 13, a massive blast engulfed an arms depot at the al-Saqr military base belonging to a PMF militia in the Dora neighborhood of Baghdad. One person was killed and 13 were injured in the explosion.

While hot weather and negligent storage were blamed for the incident, some have called for investigations into the explosion, claiming that foreign hands may have been behind the attacks.

In July, an airstrike blamed on an ISIS drone hit a PMF base in Amerli, Diyala province, injuring two PMF fighters. Two Iranian advisors working with the PMF were injured in the strike.

Speculation on who is behind the attacks is swirling. Israel, which fears Iran could be using Iraq to store weaponry, is one of the suspected perpetrators.

“We will act — and currently are acting — against them [Iran], wherever it is necessary,” Israeli Prime Minister Benjamin Netanyahu was reported as saying in an August 19 hotel briefing in Ukraine by The Times of Israel.